One type of commercially available processing chamber has a cylindrical interior. A plurality of feedthrus are disposed on each of the two end walls of the processing chamber. Each feedthru passes entirely through its corresponding end wall. A mounting flange having six holes is provided for each feedthru. An appropriate fastener is directed through each of these holes so as to detachably interconnect each feedthru with its corresponding end wall. Each of these penetrations of the processing chamber is sealed since processing in the chamber is commonly done under a vacuum. In this regard, the process may generally be referred to as a vapor film deposition where gases directed into the sealed processing chamber are ionized or fractionated. This process may be used to deposit a layer on a wafer to define a magnetic recording media (e.g., a hard disk).
A filament is mounted on each of the two end walls of the above-noted processing chamber to function as a cathode or an electron emitter. Two filament posts are each detachably interconnected with a separate feedthru (e.g., a “filament feedthru”) by a barrel connector. Each barrel connector is detachably interconnected with its corresponding filament feedthru by a set screw. There is a press fit between each barrel connector and its corresponding filament feedthru leg. In this regard, a cylindrical insert spring of sorts is disposed within each barrel connector to provide the press fit with the corresponding filament feedthru. Both filament feedthrus on each end of the processing chamber allow an electrical signal from outside the processing chamber to be directed to the corresponding filament post on the inside-of the processing chamber, and then to the filament.
The above-noted processing chamber further includes a pair of anode assemblies that each define an electron collector surface. These two anode assemblies are also mounted on each of the two end walls of the processing chamber. Each anode assembly includes three feedthru legs that are each detachably interconnected with their own separate feedthru (e.g., an “anode feedthru”). These three anode feedthrus for each anode assembly allow an electrical signal from outside the processing chamber to be directed to the corresponding anode assembly on the inside of the processing chamber.
The above-noted anode assemblies are not directly mounted on the three anode feedthrus. Instead, a barrel connector is disposed between each anode feedthru leg and its corresponding anode feedthru. Each barrel connector is detachably interconnected with its corresponding anode feedthru by a set screw. There is a press fit between each barrel connector and its corresponding anode feedthru leg. In this regard, a cylindrical spring of sorts is disposed within each barrel connector to provide the press fit with the corresponding anode feedthru leg.
There are number of problems with the above-noted configuration. One is that the cylindrical insert spring in each barrel connector may have its electrical conductivity adversely affected over time due to exposure to the plasma within the chamber. Another is that particularly those cylindrical insert springs on the barrel connectors mounted on the anode feedthrus tend to lose their resiliency over time, and thereby their ability to appropriately grip their corresponding anode feedthru leg. This may then cause the corresponding anode assembly to droop. Drooping of an anode assembly in this processing chamber configuration is undesirable in that it may have an adverse effect on the plasma, and thereby on the plasma processing of a product within the processing chamber (e.g., a film having an unacceptable film thickness variation may be formed on a wafer). Another problem is that in order to address this condition, the anode assembly must be pulled out from each of the interconnecting barrel connectors between the anode assembly and its corresponding anode feedthru. Each anode feedthru must then be detached from the processing chamber to allow its corresponding barrel connector to be detached therefrom by loosening the corresponding set screw. That is, this set screw is not accessible when the barrel connector is mounted on an anode feedthru in the processing chamber since the same is disposed within a recess or well on the end of the processing chamber. Removal of the anode feedthrus raises a number of issues, including breaking the seal of the processing chamber. Another is the potential for misalignment of the anode assemblies when re-installed on the anode feedthrus, which may have an adverse effect on the plasma process and thereby on the product being plasma processed. Finally, the insert springs on the barrel connectors are not readily replaceable instead the entire barrel connector is typically replaced.